The present invention relates to a method and apparatus for pouring molten material, such as molten metal, into a casting mold so that the amount of molten material can be weighed in connection with the pouring. In order to keep the pouring height of the molten material low and its motion as even as possible during the casting operation, the bottom of the ladle containing the molten material is designed to be essentially curved, having such a radius of curvature that the thickness of the molten layer located in the ladle is, even at maximum, only a fraction of the radius of curvature of the bottom. The casting method of the invention is advantageously realized by means of a ladle bearing apparatus according to the invention.
The casting of molten metal and its weighing in the same connection is essential for instance when casting metal anodes, because the next process step after casting is electrolysis, where one prerequisite for achieving a high efficiency is a uniform quality of the anodes, with respect to both shape and weight. In most known methods, anodes are nowadays cast in open molds.
Anode casting is generally accomplished by inclining the ladle by means of a hydraulic cylinder, which tilts the cradle on top of which the ladle is arranged. The cradle and the other end of the hydraulic cylinder are attached with bearings to a bridge. The cradle, the hydraulic cylinder and the bridge float on top of a complex leverage, which transforms the vertical forces directed to the ladle to a force which can be measured by one or several traction sensors.
In the prior art there is known a method and apparatus described in the Canadian patent 924,477 for weighing molten material in connection with pouring. This patent introduces a ladle with a curved bottom, wherein the height of the molten layer at the beginning of the casting process is of the same magnitude as the radius of curvature of the bottom. When the height of the ladle is of the order of the radius of curvature, the ladle must, during casting, be shifted on top of the mold. This type of solution is difficult to construct, if the ladle is supported from underneath, as is customary with ladles at present. It is also clear that the pouring height of the molten material becomes remarkably great, and this makes it splash. The U.S. Pat. No. 3,659,644 describes a similar type of ladle where the height of the ladle is of the same order as the radius of curvature.
In the prior art there are also known other arrangements which combine the pouring and weighing of molten material, and where the bottom of the ladle is essentially flat. In these arrangements, the pouring height of molten material is low. In some cases, the accelerating of molten material into motion from the flat bottom of the ladle may cause an erroneous impression of increased mass in the weighing sensor.